Abrading apparatus



April 1943- w. A. ROSENBERGER 2,315,546

ABRADING APPARATUS Filed Aug. 31, 1956 5 Sheets-Sheet 1 M7220? A. fiayanbc ydr SUM M N April 6, 1943. w. A. ROSENBERGER ABRADING APPARATUS Filed Aug. 31, 1956 5 Sheets-Sheet 2 Gamma/( r Aprils, 1943- w. A. ROSENBERGER 2,315,546

ABRADING APPARATU S Filed Aug. 31, 1936 5 Sheets-Sheet 3 354, JMW7W April 6, 1943. 2,315,546

W. A. ROSENBERGER ABRADING APPARATUS Filed Aug. 31, 1936 5 SheetsSheet 4 April 6, 1943. w. A. ROSENBERGER 2,315,546

ABRADING APPARATUS Filed Aug. 31, 1936 5 Sheets-Sheet 5 Gummy Patented Apr. 6, 1943 ABRADING APPARATUS William A. Rosenberger, Hagerstown, Md., as-

aignor to Pangborn Corporation, Mil, a corporation of Maryland Application August 31, 1936, Serial No. 98,783

12 Claims.

This invention relates to abrading apparatus and more particularly to abrading machines of the character wherein the work is placed upon movable supports and passed through a blasting zone.

Machines of this general character have been heretofore proposed but they have not been al-- together satisfactory because they have been of relatively high cost and have lacked the desired flexibility to handle a wide variety of sizes and Figure 4 is a iragmental vertical sectional view of one of the work supporting tables and illustrates the bearing and pulley assembly;

Figure is a vertical sectional view or the main table driving assembly of a machine shown in Figure l;

shapes of work, have been somewhat dimcult to load and unload and have been expensive to operate and maintain.

It is therefore a primary object of this inventlon to provide a novel abrading machine which will rapidly and efliciently clean articles of work of various sizes and shapes, which is low in initial and upkeep costs and which may be readily loaded and unloaded.

Another important object is to provide a novel abrading machine embodying a plurality of work. supporting tables for conveying the work into a blast zone and having means for automatically causing the tables to rotate when they attain the blast zone, so as to subject all sides of the work to the abrasive stream.

A further object is to provide an abrading machine having means for conveying articles of work through a blast zone and subjecting them to the action of a blast stream thrown from at least one mechanical abrasive propelling device.

Another object is to provide an abrading ma-- chine having novel means for supporting and rotating the work while it is in the blast zone.

Another object is to provide novel abrasive recovering means, and novel table supporting and driving means for abrading machines of the character embodying movable means for carrying articles of work through a blast zone and the invention also aims to improve and refine certain other features of such machines.

Further objects of the invention will become apparent as the specification proceeds in connection with the annexed drawings.

In the drawings:

Figure 1 is a front view of the machine of the present invention and a part of the casing has been broken away in order to more clearly illustrate certain features of the construction;

Figure 2 is a top plan view of the machine illustrated in Figure 1;

Figure 3 is a side illustration of the machine shown in Figure l, and illustrates the machine as it appears when viewed from the right hand side of that figure;

Figure 6 is a diagrammatic view illustrating the manner in which theblast stream from the centrifugal wheel is directed upon the work tables;

Figure '7 is a iragmental top plan view of the belt tensioning means of the machine shown in Figure 1 Figure 8 is a top plan view of the main table assembly with the work tables removed and the table plates disassembled to show the construction of the parts, and one of the abrasive'scrape plates is shown assembled therewith;

Figure 9 is aside elevational view of one of the intermediate arms of the machine shown in Figure 1 and illustrates one of the abrasive scrapers in place thereon;

Figure 10 is a side elevational view of one of the partition arms of the machine shown in Figure 1;

Figure 11 is a top plan view of one of the main table plates of the machine shown in Figure 1:

Figure 12 is a vertical sectional view of a modified form of mechanism for intermittently advancing the rotatable structure; and

Figure 13 is a diagrammatic top plan view of one form of mechanism that may be applied to impart rocking movement to the actuating arm of Figure 12.

With continued reference to the drawings,-

wherein like reference characters have been employed to designate like parts throughout the several views thereof, the machine briefly described comprises a housing or cabinet H in which a structure 8 is mounted for rotation about 'a substantially vertical axis.

The rotatable structure supports a plurality of work supporting tables T which are movable into the path of the blast stream discharged from blast wheel C mounted on top of the cabinet. The spent abrasive is dropped into a trough B under the machine and is carried by a screw conveyor A into the boot of an elevator E. The elevated abrasive is discharged into a hopper and conveyed to an abrasive flow,con-

trolling mechanism F and is then fed back' into 7 the centrifugal wheel. Housing H preferably is provided with a cylindrical side wall II. a flat bottom wall II and a flat top wall II. As

seen in Figure 3, the housing is provided with a front extension i4 whose side walls have substantially the same radius and curvature as walls ill of the housing so as to form a continuation thereof. Housing extension is brings the work supporting tables into aconvenient position for loading and unloading as will clearly appear which the work leaves the machine.

' The floor of the machine is reenforced by girders 2| and secured to the fioor over the central girders is a standard 22, which is secured down in any suitable manner as by means of bolts or the like. Standard 22 supports the rotatable structure. Mounted upon an anti-friction bearing 23 in a recess in the top of the standard is a relatively massive disc 24. Theby a cylindrical casing structure 58 supported upon the top of the cabinet. Casing 58 is provided with inspection and service openings 58 and 6|, and is secured to the top walls of the cabinet in any desired manner, as for instance by a plurality of brackets or the like. Bearing 58 is adapted to be lubricated by a pressure grease fitting 83 which is connected thereto by a pipe line 54. Clutch. members 48 and 52 provide a predetermined degree of lost-motionbetween the parts and function as a universal Joint shafts 39 sire is.

Shaft 53 may be rotated in any-desired manner to transmit power to shaft 39 and the rotatso as to compensate for any mis-alignment of v able structure, but preferably employed is a worm rotatable structure S comprises an upper cylin der or shell 26 and a similar lower cylinder or shell 21. Shells 26 and 2.1 are secured together by flanged joint 28 or the like and secured within shell 21, as by' means of a welding operation. or

the'like, is an annular plate 29 which'is reenforced by a plurality of gusset plates 3|.

Plate 29 is detachably secured to disc 24 by means of nut and bolt assemblies 32.

The structure Sis accordingly mounted for rotation about a substantially vertical axis in the machine and the lower edge of cylinder 21 is preferably provided with a comparatively massive ring 33 for reenforcing 'itagainst distortion under the weight of the apparatus. Secured to the outer surface of ring 33 by means of a binding strip 34 is a flexible sealing member 35.which may be made of fabric, rubber or any other desired sealing material. Seal 35 cooperates with the fioor II to prevent abrasive from ricocheting and working up into the interior of cylinder 21. In order to prevent any abrasive that might get past the seal 35 from getting into the bearing there is preferably provided a down-.- wardly extending baffle member 36 which is secured to the standard and extends in close proximity to the inner wall of cylinder 27.

The cylinders may be driven in any suitable manner but preferably the simple and compact structure shown in Figure 5 is employed. With continued reference to this figure, cylinder extends upwardly adjacent the top of the housing and is welded or otherwise secured to a drum 'member 38 which is secured to a shaft 39 by means of a key 4|. Shaft 39 is mounted for rotation in the apparatus, in a. bearing 42 which is supported in a'channel 43 carried by the cabinet. Secured to the upper wall of the cabinet by means of a binding strip 4.4 is a-sealing member 45 which frictionally cooperates with the outer surface of drum 38 to prevent stray abrahousing member 51, which is in turn supported gear 66, secured to shaft 53 by means of key 81, and which meshes with a worm 68 carried by a shaft69.

Secured to shaft 69 exteriorly of housing 51 is a sprocket wheel H (see Figures 1 and 2) which is driven by a sprocket chain 12 and a sprocket wheel 13, the latter being in turn driven by the unitary speed reducer 14 of a motor 15 supported on the top of the housing.

"From the structure so far developed, it is apparent that rotatable structure S is driven by motor 15, speed reducer l4, worm gear 66, clutch members 52 and 48', and shafts 39 and 53. The load of the assembly is taken by'thrust bearing 23, whereas the upper part of the cylinders is maintained in vertical alignment by means of bearing 42'.-

Secured to lower cylinder 21, as by means of a welding operation or the like, are a plurality of outwardly extending fins or vanes 1! to which are secured all ofthe rotatable parts of the mechanism. Secured to certain of these vanes are preferably eight table supporting arms I8, which are each provided with a web 19 for reenforcing them against downward deflection under the load of the work.

Supported on the outer end of each arm 18 (Figure 4) is a shaft '19, and mounted on each shaft i9 is a pulley 8| by means of a pair of anti-friction bearings 82 and 83. Bearing 82 is retained in a recess in pulley 8i by means of a pair of plates 84 and 85, and a plurality of cap screws 86. A sealing member 81 is clamped between plates 84 and 85 and frictionally cooperates with the outer surface of shaft 19 to prevent abrasive from working its way into the bearing. Bearing 83 is retained in a recess in the upper side of the pulley by means of a cap member 89, which is secured to the pulley by means of a plurality of cap screws 9 I. Bearing 83 is maintained in place on shaft 79 by means of a washer 92 and a cap screw 93, the latter being threaded into the upper end of the shaft. Integrally secured to cap member 89, preferably by a welding or like operation is a shaft 94 having a tapered upper end 95 and a cross pin 96. Each table is provided with a hub 91, fitting over tapered surface 95 of shaft 94, and having a pair of bifurcations 98 which embrace cross pin 98 for establishing a positive driving connection between shaft 94 and the tables. The tables may accordingly be freely lifted out of the apparatus for service and replacement. Each table is' provided with a plurality of arms iOl terminating in a circular rim I02. Seated upon the arms and rim is a perforated plate I 03 which is in turn surmounted by a perforated, preferably rubber pad I04, upon which the work is adapted to be supported. Pad I 04 being resilient, absorbs the energy of the strikes it and accordingly has a an ear I (see Figure 8) to which a strutilll is secured. The freeends of each strut are provided with anangle portion IIII, and they are rigidly secured to the intermediate portions of an arm I, which will be hereinafter referred to as a partition arm, and it is more clearly illustrated in Figure 10 of the drawings, there being one partition arm for each pair of'table supporting arms. The outer end of the partition arm is provided with a recess I080, to allow clearance for the table driving belt of the apparatus, which will be hereinafter described. Bolted or secured in any other suitable manner to the lower edge of each partltionarm is a resilient, preferably rubber, sealing member Ilflb.

' Supported intermediate each pair of table arms is an intermediate arm I III, which is also secured to fins ll, of lower cylinder 11. Thefree ends of I the partition and intermediate arms support a cylindrical band or'rim III, which is secured theretoin any suitable manner, and as seen in Figure 2, band III terminates closely adjacent to, but is spaced from the side walls I. of the cabinet. Supported on the upper surface of arms I", H and rim III, are a plurality of perforated plates H2, and as seen in Figure 11, they are provided with semi-circular openings Hi to provide. a clearance about the hubs of tables. Alsosecured to plates III are av plurality of stripsllia and 2b, which overlap the neighboring plate and seal the joint. 7

The rotatable structure accordingly. provides what is in effect a large table defined by the upper surfaces of the plates H2, and upon which are mounted a plurality of small tables T, which are bodily conveyed by the large table and are mounted for independent rotation about their axis. The abrasive which falls through the perforations in plates H2 drop onto the upper surface of floor II where it is swept or propelled around to abrasive conveying trough B by means of a scraper assembly that will now be described.

Referring to Figures 8 and 9, a scraper assembly is preferably mounted on each intermediate arm IIII (which are four in number) and each scraper comprises a member providing horizontal portions Ill and III which, as seen in Figure 8, are inclined with respect to a radius. Portions H4 and II are provided with brackets IIS and "1, respectively, and each bracket is provided with an elongated opening III. Bolt and nut assemblies H9 cooperate with the brackets and with openings in the intermediate arm to support the scraper upon the rotatable structure.

The scrapers are so mounted on arms I II) as to have a predetermined clearance with respect'to floor II. The proper adjustment may be readily effected by loosening bolt and nut assemblies I I9, raising or lowering the scrapers and then tightening the parts to hold them in locked position. As previously pointed out, the abrasive drops onto floor II, and by reason of their inclination portion H4 pushes the accumulated abrasive outwardly and portion Iii pushes the abrasive insive against rebounding out or the machine. Also, sealing strips its?) terminate close to the floor of the machine and provide-a joint that is substantially'abrasive-tight'. I Although any suitable abrading apparatus ma be employed for discharging a stream or streams of abrasive downwardly. upon the work supported. upon the tables, I preferably employ a centrifugally operable wheel assembly, mounted within 10 an open bottomed cabinet I25 over an opening in the top wall of the main housing. As more clearly illustrated in Figure 8, the apparatus comprises a wheel or rotor I20 having a plurality of substantially radial blades I 21 secured thereto and which terminate short of the .axis to provide an abrasive admitting space in which an abrasive feeding device I28 is located. Chamber "I28 mounted with an outlet I29 for feeding the abrasive over the inner ends 'of the blades. In

order to prevent the abrasive from choking, to

also impart an initial velocity thereto, an impeller IlI is secured to rotor I28 and extends with in chamber I28. Rotor Ill is driven'at high speedby means of a motor I33 mounted on the top of the cabinet and which is connected to sive control mechanism.

35 chine with its axis disposed at a different angle,

than that shown. For instance, the wheel may be arranged to discharge the fan-like stream transversely to the path of .movement of the work if desired.

As seen in Figure 6, the abrasive discharged from the wheel assumes a fan-like configuration and is discharged downwardly from the work supported upon tables T, while the table move forwardly bodily in the direction indicated in that figure, and while they simultaneously rowardly, thereby forming a concentrated pile of abrasive in front of each scraper. As each scraper attains a predetermined position in the tate about their axis in the direction indicated. Tables T are caused to rotate in this manner by the structure that will now bedescribed.

Mounted on the top of the cabinet is a motor I31 having a unitary speed reducer assembly I terminating in'a power shaft I39 carrying a sprocket Ill. A sprocket chain I42 meshes with sprocket Ill and drives a sprocket J43 carried by a shaft I. Shaft I extends downwardly outside of housing H and is journalled in a hearing I45. Mounted on shaft I adjacent bearing I45 is a pulley I46. Journalled on the opposite side of the cabinet is a pulley I41. Mounted on the back of the cabinet is an idler pulley assembly more clearly shown in Figure 7 and which comprises a standard I49 upon which a pair of bell crank levers I5I are pivoted by means of a shaft I52. Bell crank levers I5l support an idler pulley I53 and they are urged toward belt-tightening position by means of a tension spring I". Spring I54 is anchored to a bolt member I" which passes through a bracket I58 supportedon the cabinet. Bolt member I55 may be adjusted 7 to increase or decrease the tension of spring I in Figure 2, one reach of belt it! passes through tion indicated in Figure 2. If desired, however,

the direction'of belt I59 may be reversed so as to cause the tables'torotate in the opposit direction. In view of the fact that the tables rotate continuously while they are in the blasting zone, all of the upper surfaces of the work are subjected to blasting streams at different angles and are subjected to the most intense part of the blast stream. When the tables pass out of the blast zone, they become disengaged from belt i59 and come to rest, so that by the time they reach the front of the cabinet, or the loading and unloading station, they are stationary and the work may be readily removed and replaced by new work. If desired, however, if the work requires a further cleaning action, the work may be left upon the tables to again pass through the blast zone. Although the speeds of the various parts will be varied to meet the desired conditions under which it is desired to operate the machine, it has been found that suitabl speeds for general abrading are two-thirds R. P. M. for structure S and 32 R. P. M. for the work supporting tables.

Although I have illustrated a machine wherein the main supporting structure is rotated at a predetermined speed, so as to constantly and progressively bring the work through the blasting zone, if desired, a mechanism may be employed for intermittently advancing the table so as to causeeach table to be brought into, and caused to dwell for a predetermined time in the blast zone. In Figures 12 and 13 I have illustratedan advancing mechanism of this character.

With continued reference to Figures 12 and i3, shaft 39, which is connected to drum 68, is journalled in bearing 42 as in the first form of the invention. Secured to the upper end of shaft 39, by means of a pair of cap screws I65 and a key I66, is a sleeve or jaw clutch member I61 having inclined teeth I68. Surrounding the upper end of shaft I39 and resting on a shoulder I69 provided on jaw clutch member I61 is a hollow hub I" of a lever I12. Lever I12 is restrained against upward displacement from shaft 39 by means of a plate I13, which engages the upper surface of hub HI and is secured to shaft 39 by means of a pair of cap screws I14. Plate I13 is provided with an annular shoulder I16 which provides a hear-- ing for hub I1I.

Surrounding shaft 39 and mounted for vertical reciprocation in hub I'll, is a jaw clutch member I11 having clutch teeth I18 at its lower end which cooperate with the clutch teeth I66 of jaw clutch member I61. Secured to jaw clutch member I11 by means of screws I19 are a pair of keys I6I which slide in guideways I62 provided in hub I1I. Member I11 may accordingly reciprocate vertically within hub I'II butls restrained against rotation withrespect thereto.

Jaw clutch member I11 is urged downwardly into cooperation with the teeth of jaw clutch member I61 by means of a compression spring I99, which reacts against the bottom of plate I13. A pair of oil cups I84 are preferably provided in plate I19 and supply lubricant to an annular wick member I66, which in turn feeds onto the guideways I 82, and the other moving parts.

It is accordingly apparent that as four clutch teeth are employed on the jaw clutch members, rocking lever I12 through an arc of approximately in one direction causes jaw clutch member I11 to ride upwardly on teeth I66 of law clutch member I61 against the action of spring I69, and when it has reached the end of its idle stroke the teeth will snap into engagement. Upon rocking the lever 90 in the other direction, shaft 99 and structure 8 will rock through an angle of approximately 90 by reason of the driving connection established by keys IN and jaw clutch members I61 and I11.

Although lever I12 may be reciprocated in any suitable manner by any suitable means, in mg ure 13 there is diagrammatically illustrated one form of mechanism that may be used. With continued reference to this figure, lever I12 is connected to an actuating lever "I by means of a link I92. Lever I9I is pivoted for oscillation about an axis I93. mation and cooperating with the flanges thereof is a roller I94 carried by a crank pin I96. The crank arm carrying pin I 96 (not shown) is mounted for rotation about an axis I96 and is driven by any suitable prime mover at any desired suitable speed.

With crank pin I96 rotating in the direction illustrated in Figure 13, it is apparent that roller I94, operating between the channels of lever I9I, will rock lever I12 counter-clockwise and advance the table 90 and will then rock lever I12 clock wise .during a retracting or idling stroke to bring the Jaw clutch members into locking relationship preparatory to another advancing stroke. In view of the fact that when the parts are undergoing the advancing stroke, roller I94 is disposed to the right of axis I96 and therefore possesses a comparatively short lever arm with respect to axis I96 of the lever, levers I9I and I12 will move comparatively rapidly and thereby relatively rapidly advance the table. On the other hand, when roller I94 is moving through an are disposed at the left of pivot I96. Lever I9I will move comparatively slowly to bring the parts into retracted condition. Therefore, the mechanism even though driven at constant speed, will advance the work comparatively rapidly and then permit it to dwell in the blasting zone for a comparatively long period during the retracting stroke of the mechanism.

' Although the jaw clutch members have but four teeth, and eight tables are employed in the machine, which makes it necessary to place two tables in the blast zone during each advance of the main table, if desired, the number of teeth on the jaw clutch members may be increased to eight so that the tables may be brought into the blast zone one by one.

Although the inclination of the teeth in the device shown in Figures 12 and 13 is such as to rotate the table in the opposite direction from that shown in Figure 1, it is to be understood that the machine functions in the same general manner and that the direction of the jaw clutch teeth may be reversed to impart rotation to the table which is similar in direction to that of the machine first described.

Although there has been shown a rotatable structure which bodily conveys the auxiliary tables in diflnite circular paths, it is to be understood that if desired the conveying means may take the form of a mechanism for causing the Lever I9! is of channel fortables totravel inrectilinear paths joined by curvilinear paths without departing from the spirit of the invention.

Reviewing the operation of the apparatus, the various motors, are started and a worker is stationed at the front of the machine and places the work to be cleaned upon tables T as they successively arrive at the loading and unloading station. The control mechanism F is then actuated to discharge the proper grade and quantity of abrasive into feed conduit I35, whence it flows to the centrifugal wheel and is discharged downwardly as previously described. Rotatable structure S, whether it is driven at constant speed or is intermittently advanced, conveys the work into the blast zone, efficiently subjects it to the action of the blast stream and then conveys it to the unloading station where it is removed and replaced by new work.

The abrasive which rebounds from the work and other parts of the apparatus is prevented from escaping by the walls of the housing and also cylinders 28 and 21 and drops upon the main table surface, where it passes through the perforations thereof and drops upon the floor. The scraper assembly then carries the abrasive to trough B where it is conveyed to the elevator by screw conveyor A. The abrasive is lifted into an abrasive washing and separating device (not shown) where any casting fragments, nails and other extraneous material is removed and the fins and dust are also separated out. In order to prevent the surface of plates H2 between the tables from being excessively abraded I preferably provide a plurality of rubber pads I98 between the tables and which may if desired be perforated to facilitate draining the abrasive to the floor of the machine.

In order to prevent dust and fine abrasive particles from finding their way into the atmosphere the cabinet is preferably provided with a pair of exhaust conduits V which are connected to a suction fan and dust collector assembly (not shown). Suction pipes V place the interior of the cabinet under a slightly sub-atmospheric pressure, thereby preventing dust leakage into the atmosphere, even when flaps 18 are pushed aside by th work in entering and leaving the cabinet.

The invention may be embodied in other specific forms without de arting from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. In an abrading apparatus, a housing constituting a blasting chamber, a structure mounted for rotation within said housing and adapted to support and present articles of work to the action of a blasting apparatus, said structure embodying an upright cylindrical member terminating in a shaft projecting abovethe top of said housing, means for journalling said shaftupon said housing, a second shaft journalled upon said housing in alignment with said first shaft, 9. universal joint coupling said shafts for synchronous rotation, and means for driving said second shaft.

2. The abrading apparatus described in claim 1, wherein said first shaft is joumalled in a casing mounted on said housing and said second shaft is journalled in a worm gear housing mounted on the top of said casing and carries a worm gear meshing with a worm mounted for rotation in said worm gear housing.

3. In an abrading apparatus, a structure mounted for rotation about a substantially vertical axis, a plurality of horizontally disposed arms radiating from said structure and rotatably carrying work supports near their free ends, a plurality of elements radiating from said structure intermediate said arms, said elements being longer than said arms and carry g a generally circular rim at their outer ends, a plurality of struts interconnecting the free ends of said arms and the intermediate portions of certain of said elements, and a plurality of table-forming plates carried by said elements and said rim, said plates being disposed at a level intermediate said work supports and the free ends of said arms.

4. The abrading apparatus described in claim 3, wherein said structure is disposed within a cylindrical housing having a vertical cylindrical wall surrounding but spaced from the periphery of said circular rim for preventing abrasive from leaking therebetween, said wall terminating substantially flush with said table-forming plates throughout a substantial are for providing a low level loading and unloading station.

5. In an abrading apparatus, in sub-combination, a work supporting table-assembly comprising a substantially vertical shaft for rotatably supporting said table, a pulley iournalled upon said shaft by means of at least one anti-friction bearing, a cap member detachably secured to the upper side of said pulley and operable to maintain said bearing in place, said cap member also being provided with an upwardly extending portion, and a work supporting table supported upon said upwardly extending portion of said cap member for synchronous rotation therewith.

6. In an abrading apparatus, a structure mounted for rotation about a substantially vertical axis in a housing, said housing having a floor, sides and a roof, a plurality of arms radiatingfrom said structure and rotatably carrying work supports near their outer ends, means for directing at least one blast stream downwardly upon said work supports, a plurality of elements radiating from said structure intermediate said arms, said elements being longer than said arms and carrying a generally circular rim at their outer ends, a plurality of table-forming plates carried by said elements and said rim, said plates being disposed at a level intermediate said work supports and the outer ends of said arms, said elements also comprising vertical partitions of considerable area extending downwardly into close proximity to the floor of said housing for preventing abrasive from rebounding out of the apparatus.

7. The abrading apparatus set forth in claim 5, wherein said anti-friction bearing comprises an outer race piloted in a recess in said pulley and an inner race encircling said shaft, said cap 'memher having a flange piloted in said recess and operable to maintain said outer race in position therein, and a plurality of screws passing through apertures in said cap member and maintaining the same in clamping engagement with said pulley.

8. In an abrading apparatus, a work supporting structure providing a shaft portion having a plurality of axially directed ratchet teeth, said shaft portion having a reduced diameter shaft projecting beyond said teeth, a hollow hub eleing a plurality of axially directed teeth coopersting with the ratchet teeth 02 said shaft por tion, and means for resiliently urging said pawl toward said shaft portion. v

9. The abrading apparatus described in claim 8, wherein said hub element is -jouriialed at one end directly upon said shalt portion and at its other end is ioumaled upon a plate detachaloly secured to said shaft.

10. In an abrscling apparatus, a structure mounted for rotation about a substantially vertlcal axis, a plurality oi horizontally disposed arms radiating from said structure, rotatable work supports mounted on said arms, a plurality of elements radiating from said structure inter== mediate said arms, a generally circular rim mounted on the outer ends of said elements, e plurality of struts interconnecting said arms and the intermediate portions of said elements, and a plurality oi table-forming plates mounted on said elements and said rim, said plates being disposed at a. level intermediate said work supports and sold arms.

ll. The stimulus apparatus described in claim lo wherein said structure is disposed within a cylindrical housing leaving it vertical cylindrical wall surrounding lout spaced from the periphery of said oirculsr rim for preventing eloresive from leaking thereloetweeri, said well terminating substeutialiy flush with said telole=formlue plates throughout e. substantial arc ror providing a low level. loading and unloading station.

12. In on ebrediut; apparatus, a housing,

, moons on sold housing to project a stream oi etbraslve therein et lolestine velocity to define 2i blasting zone, and means to convey vvorlr through said blasting zone comprising a substantially vertical member in said housing, a substantially ver ticel cylindrical shell of a materially greater cli ameter than said member encircling and spaced from said member, a bearing between so upper part of said cylindrical shell and said verticel member to roteteloly mount said shell, as plurslity of radiating arms supported by and extending radially from s section of said shell adjacent the bottom thereof, woris supporting means on said arms, and means to eflect rotation oi said shell to move said work. supporting means into me! out oi said blasting zone.

WM. A. RQSENBERGER. 

